I had contributed on the other thread regarding the multitudes of religions, but I’ll try a different approach here. Christianity is true because the Catholic Church holds the truth. I’ve presented the arguments for the faith (accounts of Jesus, conversion of Paul, martyrs, etc), so now I’ll try approaches from the negative. Again, this approach (like my ‘numbers’ approach) isn’t typically capable of converting someone, but hopefully it can dispel doubts.
So the typical argument against Christianity is that it was done to gain power. I’ve already discussed the gains made by the early Christians (the crown of martyrdom at the hands of pagans), which isn’t something people willingly jump into. Then you can look at the early missionaries who moved to convert the pagan tribes of Europe and beyond. Most of those people also didn’t fare well (illness while traveling, beatings, murder, etc). The ones who did didn’t reap the riches from these people (who had few if any riches), but rather rejoiced in the conversion of souls. Not something you normally care about when you are after power and wealth.
So now we are in the dark ages and monarchies begin to submit themselves to the Church, most notably with Charlemagne being crowned Emperor by Pope Leo III. This gave a level of protection to the Church, but it also made it the victim of heresies and attacks. Muslims began raiding kingdoms and trying to establish themselves in the Middle East (Jerusalem) and Europe (i.e. Spain). These were not peaceful migrations, but violent conquests. To maintain peace, the monarchs used force to drive out the Muslims and try to regain control of their lands. There were certainly injustices committed on the side of Catholicism, but one must determine whether this was the Church herself or simply monarchs who happen to be Catholic (even acting in what they believe they should do for the Catholic faith).
Let’s jump to the Reformation. A strong tide against the Church splits off a significant piece, which then rebels against the Catholic Church and the Papacy. Catholics are imprisoned, martyred, and otherwise persecuted, particularly in public life.
Fast forward big-time now and look at the Church today. Scandalized, she has become the favorite punching bag of the media regarding sexual abuse. There is no excuse for what was done, but remember that what the Church did was the same that schools, youth sports, youth organizations, and other groups did as well. However, those stories aren’t as interesting as abuse in the Church. Now, Catholics are attacked as outdated, hateful bigots for our commitment to the sacred nature of marriage, the belief that life begins at conception, and other claims to the Truth. Would it not be easier to bend the knee to the Zeitgeist? Would people not rejoice if the faith of their childhood changed to meet the beliefs they hold today? How many people would flood back to the Church if she gave up her teachings on homosexuality, birth control, etc? But that isn’t the way, the truth, the life.
One final thought - the Church has never targeted the rich, the powerful, the ones in control. This faith was built by fishermen, hermits, peasants. It thrived in the shadows, behind closed doors, in the catacombs. She grew into something mighty, which is great for the conversion of souls but also difficult because her entire body on Earth is comprised of sinners, but that was not her origins, nor was it her intent. Salvation of everyone, regardless of status, is the Church’s sole mission.